4.2.3.6 Other Control Structures

The “all solution” predicates recognize the following construct as
meaning “there exists an X such that P is true”, and
treats it as equivalent to P. The use of this explicit
existential quantifier outside the setof/3 and bagof/3
constructs is superfluous and discouraged. Thus, the following two
goals are equivalent:

X^PP

The following construct is meaningful in the context of modules
(see ref-mod), meaning “P is true in the context of the M module”: